Heretofore, multiple nut type fastening units have been utilized. One of the better known previous structures consists of stamped metal plates having two threaded holes on fixed centers, and known in the art as Plate Nuts. The two threaded holes in this previous construction, being on fixed centers, do not lend themselves to use accommodating a broad range of hole spacings in a workpiece.
The Plate Nut has found acceptable use for various specific fastening needs, such as for attaching two coupling flanges of pipes. As will be apparent, the Plate Nut with at least two threaded apertures is positioned on one side of the abutting flanges and the bolts are inserted and hand-tightened from the other side. Only one wrench is needed for tightening the bolts since the Plate Nut holds itself at the two points where the bolts are inserted.
In the fastener industry in general, Gang Channels, Self-Wrenching Nuts, Clip-On-Nuts, and Anchor Nuts are also known and used. These prior constructions are adapted for single wrench operation, or self-wrenching, which operationally require only a single wrench applied to the head of the bolt for tightening of a bolt and nut set, with no tool applied to the nut itself. This basically is provided by having some auxiliary structure on a carrying member to apply a torque or restraining force to the nut while the bolt is torqued by a single wrench.
The Gang Channels consist of a metal channel formed so as to trap a plurality or series of nuts on roughly fixed centers. These channels are susceptible of having many different shapes and containing varying quantities and types of nuts.
Self-Wrenching Nuts are nuts specially designed for particular applications. In this case, a part of the nut interferes with a stationary portion on a part being joined as the bolt is relatively rotated during assembly on a workpiece.
Clip-On Nuts are of a self-wrenching variety wherein the carrying member is designed to clip over the edge of thin sheet material and hold the nut fast.
Anchor Nuts are constituted by nuts which are joined to the workpiece by secondary fasteners including such as, for example, rivets, screws, etc. The latter cannot be broadly considered as replaceable nuts, depending on the secondary fasteners used. Welding, which has been heretofore used, would generally be considered as precluding replacement or reuse. This type of fastener, generally referred to as Weld Nuts, are accordingly not considered to be prior art. If permanent rivets are used, or self-clinching types of nuts which are pressed into the workpiece are used, these likewise cannot be considered as reusable and/or replaceable nuts.
Generally the known prior art constructions have the general disadvantage that each type of unit fits only specific applications. Some, for example, are adapted for use only on the same fixed center spacings, while others fit only applications which provide appropriate interference between the nuts and the workpiece. Other prior types cannot be considered as really self-contained.
It is thus an object of the present invention to provide a multiple threaded fastener, or multiple nut assembly, adapted for single wrench fastening and which accommodates use over a broad range of variously spaced workpiece openings, and generally overcomes the drawbacks and disadvantages of previously known and used types.